This phenomenon was proposed to be akin to the appearance of complex visual hallucinations in blind people with preservation of insight, as first described by the Swiss philosopher and naturalist Charles Bonnet in the eighteenth century. Admittedly, under conditions of reduced auditory sensory input, perception-bearing circuits would be disinhibited and perceptual traces released. Musical hallucinations were also, for long time, known to be associated with acquired hearing loss, particularly in the elderly. Musical hallucinations may have different causes, namely psychiatric disorder, focal brain lesion, epilepsy, and intoxication. Musical hallucinations have been labelled Oliver Sacks’ syndrome after the British neurologist and author of the book Musicophilia. Patients may have preserved insight regarding the unreality of the phenomenon, and in this case the term musical hallucinosis should be more appropriate. Musical hallucinations are a particular type of auditory hallucinations in which the patient perceives instrumental music, musical sounds, or songs.

The clinician should bear in mind and let the patient know that improving one sensory modality to ameliorate hallucinations may sometimes paradoxically lead to hallucinations in a different sensory modality. This report emphasizes the interaction between brain pathology and sensory deficits for the genesis of hallucinations, and reinforces the theory that attention and control networks must couple properly to the default mode network, as well as integrate and select adequately peripheral signals to the somatosensory cortices, in order to keep a clear state of mind. To our knowledge, the immediate shift of hallucinations from one sensory modality to another sensory modality when perception is improved has not been previously described. However, at the same time, the patient started experiencing visual hallucinations he never had before. After using the hearing aids, the patient did not hear the songs any longer, only some tinnitus, described as a whistle. An otorhinolaryngologist diagnosed age-related hearing loss and prescribed bilateral hearing aids. There had been no previous change in medication. Five years later, the patient began complaining of musical hallucinations. The clinical diagnosis of possible dementia with Lewy bodies was established. Brain computerized tomography and nuclear magnetic resonance scans showed mild cortical and subcortical atrophy. Neuropsychological examination identified deficits in executive functions and memory tests. Neurological examination showed Parkinsonian signs and hypoacusia. He already had difficulties in instrumental activities of daily life. Case presentationĪ 71-year-old Caucasian man with hearing loss complained of memory difficulties and resting tremor of the right upper limb in the previous 2 years. Under conditions of reduced auditory sensory input, perception-bearing circuits are disinhibited and perceptual traces released, implying an interaction between peripheral sensory deficits and central factors related to brain dysfunction.

Musical hallucinations are associated with acquired hearing loss, particularly within the elderly. Musical hallucinations are a particular type of auditory hallucination in which the patient perceives instrumental music, musical sounds, or songs.

Tinnitus and hallucinations